The present invention relates to a molecule capable of binding to adrenocorticotropic hormone (ACTH) with high affinity. The present invention also relates to use of the molecule for detection and/or purification of ACTH.
Among various peptides contained in blood, some peptides show varied blood concentration in certain pathological conditions from normal conditions. Such peptides are attracting attention as disease markers in the field of clinical tests. For example, for clinical tests of Simmonds disease and Sheehan's syndrome resulting from reduction in secretion of pituitary hormones, kits for ACTH detection are used which utilize antigen-antibody reaction.
However, preparation of antibodies which are used for antigen-antibody reaction is extremely complicated and quality control of antibodies is also difficult.
Alternative to the methods utilizing antigen-antibody reaction, new peptide detection methods, i.e., detection methods utilizing aptamers which are nucleic acid molecules specifically binding to target peptides have been recently developed. For example, WO 2003/078623 discloses a method for producing an aptamer which is capable of binding to a target protein with high affinity and contains a modified nucleotide.